1. Field of the Invention
The present invention relates generally to toothbrushes and specifically to a toothbrush bristle and holder configuration providing better removal of microbial plaque accumulation from the exposed and subgingival surfaces of teeth.
2. Description of the Prior Art
Plaque control retards the formation of calculus and is critical in the prevention of periodontal disease. The development of gingival inflammation and dental cavities is usually caused by an accumulation of dental plaque on the subgingival tooth surfaces and, to a lesser extent, materia alba on the gingival surface in the subgingival space. Dental plaque is formed by oral microorganisms which synthesize harmful products that are destructive to the tooth and gum when not removed. Both dental plaque and materia alba can form within several hours, and therefore frequent mechanical cleansing is essential. Cleaning the narrow interproximal spaces between the teeth and the gingival sulcus surrounding the teeth is difficult with a conventional toothbrush. In addition to the problem of holding the toothbrush in the correct posture to enter these spaces, the sharp points of conventional toothbrush bristles can damage the gingiva in the interproximal embrasure and subgingival space when the bristle tips stray from the teeth surfaces. Studies show that the most aggressive mechanical cleaning should be directed toward the tooth surface, much less so toward the gingival surface and none toward the base of the gingival sulcus. The basis for these observations is as follows. Materia alba accumulation on the gingiva which consists primarily of an acquired bacterial coating and desquamated epithelial cells, leucocytes and a mixture of salivary proteins and lipids is a soft sticky deposit less adherent than dental plaque. It can be flushed away with a water spray but more completely removed from the gingiva with mild mechanical cleansing. Also, the gingiva can become sensitive to mechanical trauma because the toxins formed by oral microorganisms cause cellular damage to the gingiva with subsequent inflamation or gingivitis. When gingivitis occurs, vascular dilitation, capillary proliferation, engorged vessels and sluggish venous return causes a stretched and thinned epithelium that is sensitive to mechanical trauma such as aggressive brushing or abrasion from a sharp tooth pick or the like.
Dental plaque is harder and more adherent than materia alba. Removal requires much more aggressive mechanical cleansing than is required to remove materia alba from the gingiva. However, exposure of the root surface can occur due to faulty or aggressive brushing by repeated direct trauma to the base of the sulcus with the sharp point of a bristle or toothpick.
The teeth in a set are typically of different sizes and curvatures. Heretofore, the bristle supports of toothbrushes have typically been rigidly mounted to the end of the toothbrush handle, and the length and width of a conventional bristle support exceeds the distance between midpoints of adjacent teeth. The surfaces of the teeth in the interproximal embrasures are not contacted by the bristles of the bristle support, particularly if the bristles are stiff.
Another disadvantage of prior toothbrushes is that it is difficult to clean the subgingival surfaces of the teeth by the "up and down" motion of conventional toothbrushing. This is because the sulcus is relatively shallow and it is difficult while brushing one's teeth to judge how deeply to penetrate the sulcus before injuring the base of the sulcus. Consequently, there is a tendency to avoid penetrating the sulcus.
Because the teeth and gingiva have poor sensory perception, the user of a toothbrush must rely on the brush design to assure proper position and pressure of the cleansing elements against the tooth surfaces.
A variety of cleaning devices are available to remove the plaque and soft debris not easily accessible to conventional toothbrushes. Dental floss is used to clean these areas, although the proper application of floss requires considerable manual dexterity. Further, concave root surfaces cannot be reached with dental floss. Toothpicks or the like can be used with or without holders, as disclosed in U.S. Pat. No. 3,892,040. The small tip of a tooth pick allows good tooth visibility. However, the sharp point and lack of cleaning edges on the side of the toothpick prevent efficient cleaning, while presenting a potential for gingival damage. An apparatus for cleansing adjacent faces of the teeth as disclosed in U.S. Pat. No. 3,660,902, has a rotatable engagement of the cleansing tool and handle to assist in tooth contact but the point and opposite abrading faces of the tool can damage the gingival sulcus and adjacent gingival surface.
Interdental brushes such as disclosed in U.S. Pat. No. 4,222,143 are useful for cleaning large, irregular or concave surfaces adjacent wide interdental spaces, but cannot be used in the narrow gingival embrasures. Generally, the bristles are not stiff enough to exert sufficient pressure to remove plaque while thin enough to enter the interdental spaces. Again, the bristle tips present a potential for gingival damage.
As disclosed in the pending U.S. patent application Ser. No. 293,749 by Spademan, the tooth bristle cleansing head should have a shape, spacing and surface configuration for removing dental plaque from the interproximal embrasures and the exposed and subgingival surfaces of a tooth while minimizing damage to the gingival tissue facing the tooth and in the base of the sulcus.